1. Field of the Invention
The present disclosure relates to inputs for logic components, and more particularly to ground open inputs and voltage open inputs.
2. Description of Related Art
Conventional topologies for ground open inputs provide a ‘ground’ indication to a logic component if a monitored load is connected (or provides a path to ground) and to provide an ‘open’ indication if the monitored load is not connected (or does not provide a path to ground). It is also a requirement to provide a specified current to the load. The conventional topologies are restricted in their operating range when the circuit has a power supply voltage that varies over a wide range. This problem is exacerbated by tolerance of the input voltage thresholds that are required by individual logic devices to register a logic high or logic low. Therefore, a conventional circuit must register a logic low when the voltage supply is at its maximum voltage while the logic input threshold is at its minimum voltage, as well as register a logic high when the voltage supply is at its minimum voltage while the logic input threshold is at its maximum voltage.
The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved input devices. This disclosure provides a solution for this problem.